feat: update plugin @netlify/plugin-nextjs to version 4.3.2 (#705)

* feat: update plugin @netlify/plugin-nextjs to version 4.3.2

* chore: 🚩 remove feature flagged 4.3.1 entry

Since we're changing the default to 4.3.2 the flag is no longer needed

Author: ericapisani

site/plugins.json

@@ -477,14 +477,10 @@
     "name": "Essential Next.js",
     "package": "@netlify/plugin-nextjs",
     "repo": "https://github.com/netlify/netlify-plugin-nextjs",
-    "version": "4.2.8",
+    "version": "4.3.2",
     "compatibility": [
       {
-        "version": "4.3.1",
-        "featureFlag": "build_plugins_use_prerelease"
-      }, 
-      {
-        "version": "4.2.8",
+        "version": "4.3.2",
         "migrationGuide": "https://ntl.fyi/next-plugin-migration"
       },
       {